"I think he melted down last night. I think this was the turning point," the South Carolina senator who's also running for president said on Fox News "America's Newsroom."
Trump told Iowa voters that those who support Carson are "stupid" to believe the "crap" that is his life story, part of a stunning 95-minute speech
that included some of his most aggressive attacks yet on his closest competitor in the GOP primary polls.
Trump repeated similar comments he made earlier on CNN's "Erin Burnett OutFront" comparing Carson's self-described "pathology" related to his anger issues to that of a child molester.
"I said that if you're a child molester -- a sick puppy -- you're a child molester, there's no cure for that," Trump told the Fort Dodge crowd.
Graham defended Carson as "a good and decent man."
"If Dr. Carson is ever going to hit anybody in the head, it's going to be Donald Trump after everything he said," Graham said, a reference to a story from Carson's childhood where he said he hit someone with a padlock.
Trump also attacked Graham's foreign policy Thursday, questioning the war veteran's plans in defeating ISIS.
Graham has had a contentious relationship with Trump since he decided to run for president. Most notably, Trump revealed Graham's personal cell phone
number during a press conference this summer, leading Graham to publicly destroy his phone
But Graham said Friday that Trump is in no position to question anyone's foreign policy.
"Donald Trump is the most uninformed person I've ever met running for president when it comes to foreign policy. He has no clue what he's talking about," he said. "Do not replace Barack Obama with Donald Trump. It will get worse, not better."
"Mr. Trump's view of the world is pretty delusional when you look at it. He has no idea what he's talking about," Graham added. "What he's saying is going to hurt us for generations to come with Hispanics."
Graham told Republican voters Friday at the Sunshine Summit that Republicans need to be proactive in connecting with minority communities.
"To those who say Republicans have to be socially liberal to win an election -- you don't know what you're re talking about," he said in Orlando, Florida. "Republicans have to reach out to faith-based minorities who share our values and form a coalition."
The South Carolina senator said the values of many Hispanics would fit with the Republican Party.
"They're entrepreneurial. They're pro-life. They're very patriotic," he said. "We're down to 27% of the Hispanic vote in 2012. I've never seen a better opportunity for the Republican Party to rebuild its relationship with the Hispanic population than right now."
Obama has been "a lousy president for people of color," Graham added, which gives Republicans a chance to reach out to minorities.
"There are churches full of people in the Hispanic and African-American community that believes just like you do," he told the crowd. "Who's the most pro-life demographic in all of America? Hispanics. Anybody believe in traditional marriage? What group in America believes in traditional marriage the most? African-Americans."